ISLAMABAD (Dawn): Meteorologists have been rushed to investigate two glacial lakes that burst out in Gilgit-Baltistan region recently, causing flash floods and disrupting traffic on Karakoram Highway (KKH). Deputy Commissioner Hunza Usman Ali told Dawn that a lake formed atop the roughly 20 kilometre-long Hussaini glacier in Gojal Valley burst its banks at three or four points on May 7 and the rushing waters damaged some agricultural land but spared the settlements down below.

“Such flood waters bring down a lot of debris and boulders with them,” he added to explain the closure of the under-construction KKH between Gulmit and Passu for several hours. Another glacial lake burst its banks in Bargot Valley the next week. Water gushed out for hours from the burst but the people of six villages down below, and their properties, remained safe, according to Pakistan Meteorological Department (PMD) in Islamabad.

Deputy Commissioner Usman Ali sounded worried about the seven or eight more lakes that have been formed on the Hussaini glacier that could be hazardous to settlements at lower grounds. Officials of the federal government’s Climate Change Division said that the flooding caused by the two bursting lakes had left residents in the Hussaini village without drinking water for at least two days.

“Glacial lake outburst floods (GLOF) have become a concern,” said PMD Chief Meteorologist Dr Ghulam Rasul explaining “the fairly unique phenomenon” to Dawn where huge lakes are formed on the surface, or water is dammed inside the walls of the glaciers. “They are particularly dangerous because the walls holding the massive water bodies can break, among a dozen other reasons, due to intense heat of the sun, torrential rains, glacial movement or seismic activity, with flash floods devastating villages lying directly in their paths,” he said.

GLOF events have become a regular feature in the valleys of northern Pakistan in the last few years. “Two GLOF events at the start of summer are indicative of what is to come when the weather gets warmer,” said Chief Meteorologist Dr Ghulam Rasul. Ground survey teams were heading to the two locations to study how the lakes burst and the damage the bursts caused, he said. The teams are likely to report their findings after a week or 10 days.

PMD’s last survey, conducted in 2013, had identified 36 dangerous glacial risks and declared them hazardous for settlements downhill if they ruptured. “What makes these lakes particularly dangerous is that the glaciers in Pakistan exist at relatively low heights, between 2,200 metres and 2,300 metres and roughly less a kilometre from the nearest settlements,” observed PMD Meteorologist Atif Wazir. In some cases, potential bursts allow only 30 or 40 minutes to sound an alarm for the threatened population to evacuate to safety, he noted.

“In Nepal glaciers lie at 4,500 metres or more. In case of a glacial lake outburst people have enough lead time to escape to safer or higher grounds in time,” he said. One of the largest and dangerous glacial lakes is the Gharko Lake in Gilgit-Baltistan. It is about 100 metres long, 77 metres wide and 27 metres deep. The Hinarchi Lake is equally unstable and capable of causing flash floods downhill.

Temperatures in the Northern Areas of Pakistan have risen by 1.5 degrees centigrade between 1990 and 2010, according to the Pakistan Meteorological Department, which has recorded five GLOF events in the last three years. “Two years ago, the Buni glacier outburst caused extensive damage to houses in its path. Gulkin glacier, close to the Karakoram Highway, bursts out frequently and now regularly feeds the Attabad Lake in Hunza,” said Dr Ghulam Rasul, recalling the formation of the lake in 2008.

Surprisingly, the number of hazardous lakes dotting Swat, Chitral, Gilgit, Hunza, Astore, Shigar, Shyok and the Indus region have decreased from 52 in 2001 to 36 today. “We are studying how some of these lakes disappeared. However, four more lakes have formed in Chitral and Hunza. Once the ground survey is complete we will know how climate change is impacting glacial melting rate,” said meteorologist Atif Wazir.

Although a $4.1 million GLOF study, funded by the United Nations Development Programme (UNDP), is going on, experts say some of its components need much improvement. Initiated in 2011, it was Pakistan’s first Climate Change Adaptation Project focusing on mitigating risks of glacial lake bursts caused by rising temperatures and other reasons.